Direct dye colorants are essential elements in hair coloring preparations for the semi-permanent dyeing of keratin fibers, such as human hair. In contrast to oxidation dyes which are conventionally developed with the aid of oxidizing agents, such as hydrogen peroxide, directly acting dyes color hair on their own, without oxidizing agents, at room temperature. Unlike oxidative dyes, semi-permanent or direct dyes advantageously do not cause the appearance of a demarcation or borderline phenomenon between the ends and half-lengths of the hair and the growing roots of the hair.
A direct dye composition for the semi-permanent coloring of hair should optimally serve to cover gray hair and to apply a new color to hair of any color. The dyed hair should be resistant to fading due to light or friction, e.g., rubbing. Semipermanent dyes should be toxicologically benign. They should be resistant to change in the hue or color if another substance is applied to the hair, such as a permanent wave and the like.
The commercially available colorant Disperse Blue 3 (DB 3) is a widely used semi-permanent hair colorant. It is actually a mixture of three blue anthraquinones, Disperse Blues 3, 14 and 23 (i.e., DB 3, DB 14 and DB 23). The mixture of DB 3, DB 14 and DB 23 is produced during the manufacture of commercially available colorant DB 3, which is synthesized by reacting quinizarin (i.e., 1,4-dihydroxyanthraquinone), or leucoquinizarin, with a mixture of 2-aminoethanol and methylamine (Ventkataraman, K., 1952, The Chemistry of Synthetic Dyes, Vol. II, Academic Press Inc., New York, p. 809; Abrahart, E. N., 1968, Dyes and their Intermediates, New York: Pergamon Press, New York, p. 176) as represented hereinbelow: ##STR1##
As those having skill in the art will appreciate, the technical name of the specific DB 3 anthraquinone is 1-(2-hydroxyethyl)amino!-4-(methylamino)-9,10-anthracenedione (International Cosmetic Ingredient Dictionary, Monographs, Sixth Edition, Eds., J. A. Wenniger and G. N. McEwen, Jr., The Cosmetic, Toiletry and Fragrance Association (CTFA), Washington, D.C., 1995, pages 350-351). DB 23 is chemically known as 1,4-bis(2-hydroxyethyl)amino!-9,10-anthracenedione, and DB 14 is chemically known as 1,4-bis(methylamino)-9,10-anthracenedione.
The mixture of different anthraquinones comprising the commercially available colorant DB 3 has been shown to be efficacious as a hair dye due to the synergistic effect of the presence of multiple anthraquinones in the mixture (Ventkataraman, K., 1952, Ibid.). However, as a direct result of the nature of the commercially available colorant DB 3 as a mixture, it has several disadvantages in hair coloring formulations. One disadvantage is the potential batch-to-batch variations in the DB 3: DB 14: DB 23 ratios contained in a product comprising the commercially available colorant DB 3; such variations are likely to affect hair dyeing properties. Another disadvantage is manufacturer-to-manufacturer variation in the ratios of the component anthraquinones (Bide, M. J. & McConnell, R. L., Textile Chemist and Colorist 28(3):14, 1996), which result in different compositions (see Table 1) and different dyeing properties. A further disadvantage is that different manufacturers may add toners of various colors, such as Disperse Violet 1 (DV 1), i.e., 1,4-diaminoanthraquinone, (Table 1); such toners will also change dyeing results. Also, the use of the mixture comprising DB 3 makes quantitative analysis quite difficult, since a chromatographic separation to resolve components and at least three quantifications are routinely necessary.
TABLE 1 ______________________________________ Compositions of commercially-available DB 2 samples analysed by HPLC* Intrasperse Brilliant Blue B Supra Artisil Blue B (Crompton & Knowles (Sandoz Corp.) Corp.) ______________________________________ DB 3 30.7% 28.6% DB 14 9.1% 4.4% DB 23 14.2% 17.3% DV 1 0% 11.3% ______________________________________ *The remainder of the samples are other colored components and colorless dispersants.
Thus, it would be an improvement and an advantage in the art to have a direct hair coloring product containing anthraquinone dyes for darker and more intense coloring of hair, but which avoid the above-listed disadvantages that are associated with the use of known anthraquinone mixtures in hair coloring compositions.
The use of 1,4-di(mono-or poly)hydroxyalkylamino-9,10-anthraquinones for the dyeing of hair is disclosed in U.S. Pat. No. 5,226,924 to A. Junino et al. The synthesis and use of specific mixtures of anthraquinones are not described. The anthraquinone dye(s) that are disclosed by Junino et al. specifically require a 2,3-dihydroxypropylamino group at position 4 of the molecule.
U.S. Pat. No. 3,368,942 to W. J. Kaiser et al. discloses water soluble aminoanthraquinone hair dyes, but is silent regarding specific anthraquinone mixtures as described by the present invention.
U.S. Pat. No. 4,834,768 to J. F. Grollier discloses dyeing compositions for the direct coloring of hair which comprise, among other dyestuffs, anthraquinones and which require the use of a xanthan gum.
Patents which disclose anthraquinone dyes for hair dyeing are U.S. Pat. No. 3,168,441 to M. Bil et al.; U.S. Pat. No. 3,449,056 to F. Pum et al.; U.S. Pat. Nos. 5,486,629; 5,360,930; 5,169,403; 5,314,505 to A. Chan et al.; U.S. Pat. No. 5,112,359 to B. Murphy et al.; and U.S. Pat. No. 5,520,707 to M.-I. Lim et al. None of these patents disclose the novel anthraquinone dye mixtures having enhanced dyeing properties and improved color intensity when used with other dyes as described by the present invention.
DE 4,031,342 discloses 1,4-bis-(hydroxyalkyl)amino anthraquinones, but does not teach or disclose particular mixtures of anthraquinones having chemical structures described for the anthraquinone components of the present invention.
The use of anthraquinone dyes such as DB 23 in the dyeing of synthetic fibers, e.g., polyolefin fibers, has been described, for example, in U.S. Pat. Nos. 2,199,813 and 3,235,322, but is clearly distinguished from the use of anthraquinone dyes in compositions for the coloring of keratinous fibers, such as animal and human hair. 1,4-diaminoanthraquinone disperse dyes have also been disclosed, in an unrelated field of art, for use on synthetic polymer substrates such as cellulose acetates, nylons and polyesters (R. S. Sinclair et al., 1975, J.S.D.C., 91:399-405.
The blue anthraquinone DB 23 has been disclosed in U.S. Pat. Nos. 4,835,314, 4,921,504, 5,030,241 and 5,037,446, but is used in each as the sole anthraquinone dye in the dye formulations. The foregoing patents do not disclose DB 23 as a component of novel anthraquinone mixtures having stronger synergistic effects than does DB 3 when used with other anthraquinones, such as Disperse Violet 1, in the dyeing of human hair.
The anthraquinone compounds and mixtures of the present invention are distinct from prior art hair dyeing compounds and offer surprising and advantageous hair coloring properties after use.